Electrodeposition of aluminum and refractory metals from non-aromatic organic solvents

ABSTRACT

An electroplating solution includes a non-aqueous non-aromatic organic solvent and a mixture including soluble metallic salts and organic additives dissolved in the non-aqueous non-aromatic organic solvent. Electrodeposition of a metal from the electroplating solution includes preparing an electroplating solution and electrodepositing the metal from the electroplating solution onto a conductive substrate under a cathodic current. An electroplating system has a plating chamber containing an electroplating solution, an entry point to the electroplating system, and a transporting system to convey a part to be electroplated from the entry point to the plating chamber. The electroplating solution includes a non-aqueous non-aromatic organic solvent and a mixture including soluble metallic salts and organic additives, the mixture dissolved in the non-aqueous non-aromatic organic solvent.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit of U.S. ProvisionalPatent Application No. 60/451,631, filed in the United States on Mar. 5,2003, the entire contents of which are incorporated herein by reference.

BACKGROUND

[0002] 1. Field of the Invention

[0003] The present method relates generally to electrodepositedcoatings. More specifically, the method relates to metallic coatings ofaluminum, magnesium and refractory metals, such as titanium, tantalum,zirconium, and their alloys, obtained by electrodeposition fromnon-aromatic organic solvents.

[0004] 2. Background of the Invention

[0005] In the description of the background of the present inventionthat follows reference is made to certain structures and methods,however, such references should not necessarily be construed as anadmission that these structures and methods qualify as prior art underthe applicable statutory provisions. Applicants reserve the right todemonstrate that any of the referenced subject matter does notconstitute prior art with regard to the present invention.

[0006] Surface protection against corrosion and wear can be applied toferrous and non-ferrous metal parts. A suitable method to obtain suchprotection is coatings. For example, in the aerospace industry cadmiumcoating is used to protect parts, such as landing gear or fastenersagainst corrosion. The cadmium coating functions as a sacrificialcoating that provides protection even when scratched. However, cadmiumis a toxic metal electrodeposited from a plating solution based oncyanide, which affects the handling and disposal precautions. Substitutemetallic coatings for cadmium are needed.

[0007] One aspect of the protection supplied by the coating is a resultof the salt water electrochemical potential of the cadmium coating beingnegative relative to the underlying material. Thus, suitable substitutecoating materials for cadmium include those materials with similar,e.g., negative, salt water electrochemical potentials relative to theunderlying material. For example, zinc, manganese, beryllium andmagnesium are included in candidate materials to replace cadmium incoatings. However, these candidate materials have drawbacks. Zinc, whileeasy to electroplate, suffers from environmental embrittlement and isthus unsuitable for high strength steels. Manganese can be electroplatedby aqueous methods, but exposure can cause pulmonary and neurologicaleffects. Beryllium similarly has environmental drawbacks and magnesiumis highly active in this application when not alloyed within a coating.

[0008] Aluminum and refractory metals, such as titanium, are substitutecandidates for protective coatings and for replacing of cadmiumcoatings. Aluminum coatings can provide a sacrificial protective barrieragainst corrosion for ferrous metal parts. Refractory metal coatings canprovide a protective barrier against damage to the underlying material,e.g., ferrous and non-ferrous metal parts, by mechanisms such ascorrosion, erosion, wear, abrasion and embrittlement.

[0009] Aluminum and refractory metals, such as titanium, are typicallyobtained electrochemically from fused salts bath chemistry, such asthose based on lithium chloride, or from toxic organic solvents, such asthose based on benzene and toluene, or by electrophoresis. These knownmethods have negative drawbacks on coating quality and cost. Forexample, molten slat bath methods may avoid embrittlement duringplating, but trapped salts can be a source of subsequent corrosion andembrittlement.

[0010] Metallic coatings of aluminum and refractory metals can also beobtained by other methods. For example, physical techniques, such as arcspraying, physical vapor deposition techniques, such as ion vacuumdeposition of aluminum (otherwise known as ivadizing), and chemicaltechniques, such as sol-gel or electrodeposition from toxic organicsolvents or by fused salts, can be employed to form coatings of aluminumand refractory metals.

[0011] U.S. Pat. No. 4,145,261 discloses a plating solution that is amixture of toluene, organics including benzene, and aluminum halides.U.S. Pat. No. 4,759,831 discloses a load-lock isolated electrolytechamber for the electrodeposition of aluminum. The nature of the platingsolution, e.g., the environmental aspects and the tendency to becontaminated when exposed to air, render this disclosed solution andprocess costly, inefficient, and potentially hazardous to theenvironment and to health.

[0012] Japanese patent 55-158289 discloses various low molecular weightorganic solvents in which were dissolved synthesized aluminum salts.However, no details on coating properties were provided.

[0013] Thus, there remains a need for coating technologies that canreplace the current cadmium coatings, particularly in high strengthsteels and aerospace applications. Further, there is a need for aluminumelectrodeposition technologies that are environmentally safe and clean,while also being cost and time efficient.

SUMMARY

[0014] An exemplary method of electrodeposition of a metal comprisespreparing an electroplating solution and electrodepositing the metalfrom the electroplating solution onto a conductive substrate under acathodic current. The electroplating solution includes a mixture ofsoluble metallic salts and organic additives dissolved in a non-aqueousnon-aromatic organic solvent.

[0015] An exemplary electroplating solution comprises a non-aqueousnon-aromatic organic solvent and a mixture including soluble metallicsalts and organic additives, the mixture dissolved in the non-aqueousnon-aromatic organic solvent.

[0016] An exemplary embodiment of an electroplating system comprises aplating chamber containing an electroplating solution, an entry point tothe electroplating system, and a transporting system to convey a part tobe electroplated from the entry point to the plating chamber. Theelectroplating solution includes a non-aqueous non-aromatic organicsolvent and a mixture including soluble metallic salts and organicadditives, the mixture dissolved in the non-aqueous non-aromatic organicsolvent.

BRIEF DESCRIPTION OF DRAWING FIGURES

[0017] The following detailed description of preferred embodiments canbe read in connection with the accompanying drawings in which likenumerals designate like elements and in which:

[0018]FIG. 1 is a schematic representation of an electroplating system.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0019] Electrodeposition from non-aromatic organic solvents (NAOS) candeposit metals and alloys that cannot be obtained otherwise byconventional (aqueous) electroplating. Since there is little or no waterpresent in solution (as in the water of aqueous solutions), hydrogenembrittlement of high tensile strength materials is reduced orminimized. In addition, NAOS processes have similar or the samecharacteristics as conventional electroplating in terms of partshandling, some equipment and methods, allowing for efficientsubstitution of NAOS in typical electrodeposition facilities.

[0020] An exemplary method of electrodeposition of a metal comprisespreparing an electroplating solution and electrodepositing the metalfrom the electroplating solution onto a conductive substrate under acathodic current. The electroplating solution includes a mixture ofsoluble metallic salts and organic additives dissolved in a non-aqueousnon-aromatic organic solvent.

[0021] The non-aqueous non-aromatic organic solvent can be any suitablesolvent. For example, a suitable solvent includes low molecular weightnon-aromatic organic solvents. In this context, low molecular weightmeans 200 g/mole or less. Such solvents include the family of alcohols,such as ethanol, propanol, isopropanol, butanol, 2-butanol and theircorresponding alcohols having more than one OH functional group,ethanolamine and amines. Carboxylic acids, such as oxalic acid, citricacid and ammonium citrate, can be used as support electrolytes or assolvents as well. In addition, plating electrolytes can have acombination of two or more of these suitable solvents. Further, althoughother families of organic solvents, such as ketones, aldehydes, alkenes,alkynes, ethers, amides and toxic aromatic compounds, can be used, thetoxicity level of these solvents make them less desirable.

[0022] Into these solvents, soluble metallic salts are dissolved. Suchmetallic salts include metal alkoxides, such as ethoxides, propoxides,isopropoxides, butoxides and their corresponding halides, phosphates,carbonates and other inorganic and organic compounds capable ofproviding metallic ions to be reduced at the cathode duringelectrodeposition. The metallic salts may be present individually orother salts plus mixtures thereof may be used.

[0023] Targeted metals for electrodeposition in the exemplary method arethose metals that cannot readily be electroplated from aqueoussolutions. Examples of targeted metals include aluminum, titanium,tantalum, zirconium, molybdenum, tungsten, niobium, osmium, hafnium,magnesium and alloys of any combination of these metals, or other metalsfrom salts soluble into the above mentioned solvents.

[0024] In the electroplating solution, the concentration of the metallicsalt may vary from 5% to 100% of the saturation concentration for therespective metallic salt in the solvent at the operational temperaturefor electrodeposition. Conductive additives, such as oxalic acid,phosphoric acid and other low molecular weight organic acids can also beadded into such electroplating electrolytes. In this context, lowmolecular weight means 200 g/mole or less. Any organic or inorganiccompound that increases the solvent conductivity and is soluble intosuch solvent may be added, either alone or in combination. For instance,in ethanol the following secondary products are soluble: sodiumhydroxide, boric acid, ammonium chloride, calcium carbonate, sodiumiodine, ammonium fluoride, aluminum nitrate, stearate or chlorohydrate,aluminum chloride, aluminum phosphate and aluminum potassium phosphate.

[0025] Minimizing electrolyte contamination promotes adhesion andcoating performance. Contamination of the plating electrolyte may leadto deposit non-uniformity, porosity, galling, pitting, blistering andmay even result in no deposition at all. There are various ways toprevent or minimize contamination of the electrolyte with air, water, orsolution or electrodeposition by-products. Electrolyte filtration and acontrolled atmosphere (e.g., where the plating solution is housed) mayboth be utilized to assist in maintaining the proper operation of theelectrodeposition bath. For example, electroplating electrolytes can becontinuously filtered on molecular sieves to minimize contamination bywater. A suitable molecular sieve for this application is a 3 angstrommolecular sieve. In another example, an inert atmosphere can bemaintained over the electroplating solution during at least theelectrodepositing of the metal on the substrate. The inert atmospherecan minimize contamination by oxygen and water, by, for example,maintaining the atmosphere in contact with the electroplating solutionsubstantially oxygen-free and moisture-free. For example, the oxygencontent can be 1-10 ppm, preferably less than 5 ppm, and the watercontent can be 1-10 ppm, preferably less than 5 ppm, but the actualconditions can vary depending on the metal being electrodeposited.Preferably where an inert atmosphere is used, the inert atmosphere iscontinually maintained over the electroplating solution. An example ofan inert atmosphere includes bubbling nitrogen through the electrolytesand/or gas regulation of a nitrogen atmosphere over the electroplatingbath.

[0026] In a further example, positive pressure inside the platingchamber can be used to reduce contamination. Preferably, the positivepressure is maintained at 1 atmosphere, but the atmosphere can be loweror higher than 1 atmosphere, depending on the sensitivity of the processand the design of the plating chamber.

[0027] In a still further example, a glove-box type or closeddouble-compartment chamber filled with an inert gas, such as nitrogen,and filtered from water and oxygen through an adequate catalyst can beused for NAOS. Electroplating solutions within the glove-box type or theclosed double-compartment chamber can be arranged as a singleelectrolyte bath or can be split into separate catholyte and anolytecompartments. Splitting into separate catholyte and anolyte compartmentsis preferred where possible decomposition of the respective solutionsdue to electrolysis may be encountered. When the catholyte and theanolyte compartments are split, the possible decomposition can becontained by, for example, a suitable ion-permeable membrane between thechambers. For plating chemistries that require splitting of theelectrolyte, a suitable ion-permeable membrane is a polymeric membrane,although a wide variety of commercial fully permeable or semi-permeablemembranes can be used. Membrane separation can also be used betweenelectrodes so as to use different anode and cathode electrolytes.

[0028] In the exemplary method of electrodeposition, suitable anodematerials include metals that are identical or similar electrochemicallyto those being electroplated, provided they do not form an insulatingbarrier upon their surface, or metals that are compatible with theelectrolyte, whether soluble or insoluble. To avoid an electrolytecontamination, suitable insoluble anodes or soluble anodes formed of amaterial including a metal that is to be plated can be used. Otherwise,other anode material such as platinized titanium, DSA-type anodes orother insoluble but conductive material can be used.

[0029] Suitable cathodic current density at the conductive substrate mayvary between 0.05 to 1000 amperes per dm², depending upon electrolytecomposition and the metal to be electroplated. In each NAOS process,electrode surface ratio is determined such that equilibrium between thequantity of metal that is dissolved from anodes and metal beingelectroplated is reached, in order to maintain chemical balance of theelectrolyte.

[0030] The conductive substrate may optionally have the surface preparedprior to electrodeposition. For example, the surface can be gritblasted, masked and then alkali or acid cleaned prior to electroplating.After alkali or acid cleaning, the conductive substrate is alcoholdipped or sprayed to remove any aqueous cleaners. In some instances, areverse etch can be used to promote adhesion.

[0031] Any type of agitation of the electroplating solution or parts ofthe solution can be incorporated into the process. For example, movingor vibrating bus-bars, nitrogen or other inert gas bubbling, orultrasonic devices can be used.

[0032] The electroplating solution temperature for each NAOS process canbe regulated such that solvent surface tension is not more thanapproximately 50% (+10%) of its vaporization pressure, or such that theelectroplating solution is chilled to improve plating conditions andefficiency. For example, the electroplating solution can be regulated bythe use of a heat exchanger or a chiller.

[0033] Electrolyte evaporation can be reduced by adding floatingdevices, such as polymeric balls or by adding a chemical compound on topof the liquid surface that prevents evaporation but allows theintroduction of parts into the bath.

[0034]FIG. 1 is a schematic representation of an electroplating system.An exemplary embodiment of an electroplating system 100, includes aplating chamber 102 containing an electroplating solution, an entrypoint 104 to the electroplating system 100 and a transporting system 106to convey parts 108 to be electroplated from the entry point 104 to theplating chamber 102.

[0035] The plating chamber 102 includes either a single electroplatingcompartment or a split compartment for anolyte and catholyte asdiscussed herein. As shown in FIG. 1, the chamber 102 contains a splitcompartment having two anodes 110, 112 arranged essentially opposingeach other with a catholyte in between. Each anode 110, 112 is separatedfrom the catholyte by a membrane 114, 116.

[0036] The electroplating solution is continuously agitated bycirculation through an external chamber 118 housing molecular sieves,which scavenge water molecules. An associated pump (not shown) helps tocirculate and recycle the electrolyte between the plating chamber 102and the external chamber 118 to assist in control of electrolyte purityand composition.

[0037] Further, an inert atmosphere is maintained within at least theplating chamber 102, preferably within the electroplating system 100, bygas regulation. In FIG. 1, the gas regulation is shown as regulatednitrogen gas tanks 120. However, any suitable inert atmosphere and anysuitable regulation system can be used. Typically, a positive pressure,e.g., about 1 atm, is maintained in the plating chamber 102.

[0038] The entry point 104 to the electroplating system 100 can be anysuitable entry point that accommodates the part 108 and can interfacewith the plating chamber 102 while maintaining adequate containment andbath vapor control. For example, FIG. 1 shows the entry point 104 as anair-lock type transfer point with a first exterior door 122 and a secondinterior door 124. Generally, operation of the exterior door 120 and theinterior door 122 is coordinated with a vacuum pump and inert gasbackfilling valve to minimize the introduction of air from outside theelectroplating system 100 into the plating chamber 102.

[0039] The transporting system 106 places the part 108 into positionwithin the plating chamber 102 for electrodeposition. For example and asshown in FIG. 1, the transporting system 106 places the part 108 intothe catholyte and in electrical contact with a source 126. The source126 may be either gravimetric or potentiostatic, depending on theelectrochemical conditions. The source 126 is also in electrical contactwith each anode 110, 112.

[0040] The transporting system 106 can include any suitable transportingsystem for the part 108. Examples of suitable transport systems includehydraulic lifts, chain lifts, conveyors, elevator systems, rack-upsystems rotating systems and so forth. For example, large parts may beracked up and electroplated from the racked position, smaller parts maybe plated in a barrel plating manner. In barrel plating, the parts areplaced in a rotating cage which rotates within the electroplatingsolution such that the parts are totally submerged within the platingsolution. In barrel plating, residual unplated points from the rackingstep are reduced to a minimum and the entire part is electroplated.

[0041] Solutions that allow the electroplating of aluminum based on NAOSare illustrated in the following examples (Example 1-Example 3):

EXAMPLE 1

[0042] Other Component Chemical name Concentration Information SolventEthanol — Aluminum Source Aluminum  0-5 g/L #1 isopropoxide ConductiveOxalic acid 0-100 g/L Additive #1 Aluminum Source Aluminum 0-900 g/L #2chloride Conductive Boric acid  0-50 g/L Additive #2 Temperature roomtemperature Anode material aluminum

EXAMPLE 2

[0043] Other Component Chemical name Concentration Information SolventEthanol-  0-50 V/V ispropanol Aluminum Source Aluminum  0-5 g/L #1isopropoxide Conductive Oxalic acid 0-100 g/L Additive #1 AluminumSource Aluminum 0-900 g/L #2 chloride Temperature room temperature Anodematerial aluminum

EXAMPLE 3

[0044] Other Component Chemical name Concentration Information SolventButanol — Aluminum Source Aluminum  0-10 g/L #1 butoxide ConductiveOxalic acid 0-100 g/L Additive #1 Aluminum Source Aluminum 0-500 g/L #2chloride Temperature room temperature Anode material aluminum

[0045] Solutions that allow the electroplating of titanium based on NAOSare illustrated in the following examples (Example 4):

EXAMPLE 4

[0046] Other Component Chemical name Concentration Information SolventEthanol — Titanium Titanium ethoxide 0-10 g/L Source #1 Conductive Boricacid 0-50 g/L Additive #1 Titanium Titanium chloride 0-50 g/L Salt #2Temperature Room temperature Anode material titanium

[0047] Solutions that allow the electroplating of tantalum based on NAOSare illustrated in the following example (Example 5):

EXAMPLE 5

[0048] Other Component Chemical name Concentration Information SolventEthanol — Tantalum Source Tantalum   0-100 g/L #1 isopropoxideConductive Oxalic acid  90 ± 15 g/L Additive #1 Tantalum Source Tantalum 0-5000 g/L #2 pentachloride Temperature room temperature Anode materialtantalum

[0049] Solutions that allow the electroplating of zirconium based onNAOS are illustrated in the following example (Example 6):

EXAMPLE 6

[0050] Other Component Chemical name Concentration Information SolventEthanol — Zirconium Source Zirconium  0-50 g/L #1 ethoxide ConductiveOxalic acid 0-100 g/L Additive #1 Zirconium Source Zirconium 0-500 g/L#2 tetrachloride Temperature room temperature Anode material zirconium

[0051] Although various anodes, cathodes, and solution chemistries canbe used in the metal deposition process, a preferred electrodepositionprocess for aluminum uses aluminum anodes and benign organic andinorganic aluminum salts and other conductivity promoter chemicals.However, both other metals and refractory metals can be obtained byelectrodeposition from organic solvents of the same functional group.

[0052] The properties of the electrodeposition method and theperformance of electroplated aluminum from the process were analyzed. Itwas found that throwing power, which is a consideration for uniformcoatings on complex structures and inner diameters, was approximatelyequivalent to the throwing power of cadmium deposition. Because thealuminum electroplating process is non-aqueous, the process does notrelease free hydrogen at the cathode that can cause hydrogenembrittlement in high strength steels. Further, and unlike conventionalcadmium, electroplated aluminum can be anodized to increase the hardnessfrom a typical 10-25 Vicker's hardness (Hv) to an as-plated coatinghardness of about 500 Hv (using the ASTM standard test protocol forVicker's Hardness in this range of hardness) contributing to reducedscratches and damage both in-production and in-service.

[0053] Among applications of the invention is the electrodeposition ofaluminum over high strength steel parts encountered in aerospace. TheNAOS processes can be applied on any conductive substrates as long asthe substrate is not susceptible to be chemically attacked by thechemistry of the plating solutions.

[0054] Although the present invention has been described in connectionwith exemplary embodiments thereof, it will be appreciated by thoseskilled in the art that additions, deletions, modifications, andsubstitutions not specifically described may be made without departingfrom the spirit and scope of the invention as defined in the appendedclaims.

What is claimed is:
 1. A method of electrodeposition of a metal, themethod comprising: preparing an electroplating solution, theelectroplating solution including a mixture of soluble metallic saltsand organic additives dissolved in a non-aqueous non-aromatic organicsolvent; and electrodepositing the metal from the electroplatingsolution onto a conductive substrate under a cathodic current.
 2. Themethod of claim 1, wherein the soluble metallic salts are a metalalkoxide.
 3. The method of claim 2 wherein the metal alkoxide isselected from the group consisting of metal ethoxides, propoxides,isopropoxides, butoxides, corresponding halides, phosphates, andcarbonates, and mixtures thereof.
 4. The method of claim 1, wherein themetal is selected from the group consisting of aluminum, titanium,tantalum, zirconium, molybdenum, tungsten, niobium, osmium, hafnium,magnesium and alloys and combinations thereof.
 5. The method of claim 1,wherein the non-aqueous non-aromatic organic solvent is a low molecularweight non-aromatic solvent.
 6. The method of claim 1, wherein thenon-aqueous non-aromatic organic solvent is an alcohol or an amine. 7.The method of claim 6, wherein the alcohol has more than one OHfunctional group.
 8. The method of claim 1, wherein the non-aqueousnon-aromatic organic solvent is selected from the group consisting ofethanol, propanol, isopropanol, butanol, 2-butanol and ethanolamine. 9.The method of claim 1, wherein a concentration of the soluble metallicsalt in the electroplating solution is from 5% to 100% of a saturationconcentration for the metallic salt in the non-aqueous non-aromaticorganic solvent at an operational temperature for electrodeposition. 10.The method of claim 1, comprising adding a conductive additive to theelectroplating solution to increase solvent conductivity.
 11. The methodof claim 10, wherein the conductive additive is a low molecular weightorganic solid.
 12. The method of claim 10, wherein the conductiveadditive is oxalic acid, citric acid, ammonium citrate or a chloride, apentachloride, a tetrachloride of the metal, or an organic or inorganiccompound soluble in the electroplating solution.
 13. The method of claim1, comprising continuously filtering the electroplating solution overmolecular sieves and maintaining an inert atmosphere over theelectroplating solution during at least electrodeposition.
 14. Themethod of claim 13, wherein the inert atmosphere maintains asubstantially oxygen-free and moisture-free atmosphere in contact withthe electroplating solution.
 15. The method of claim 1, comprisingsplitting the electroplating solution into a separate catholytecompartment and a separate anolyte compartment, the catholytecompartment and the anolyte compartment separated by a membrane.
 16. Themethod of claim 1, comprising agitating the electroplating solution oragitating a part being electroplated.
 17. The method of claim 1,comprising preparing a surface of the conductive substrate forelectrodeposition by grit blasting the surface, masking the surface,cleaning with an alkali or acid cleaning solution and removing thecleaning solution by an alcohol dip or spray.
 18. An electroplatingsolution, comprising: a non-aqueous non-aromatic organic solvent; and amixture including soluble metallic salts and organic additives, themixture dissolved in the non-aqueous non-aromatic organic solvent. 19.The electroplating solution of claim 18, wherein the soluble metallicsalts includes aluminum salts that allow the electrodeposition ofaluminum.
 20. The electroplating solution of claim 18, wherein thesoluble metallic salts includes titanium salts that allow theelectrodeposition of titanium.
 21. The electroplating solution of claim18, wherein the soluble metallic salts includes tantalum salts thatallow the electrodeposition of tantalum.
 22. The electroplating solutionof claim 18, wherein the soluble metallic salts includes zirconium saltsthat allow the electrodeposition of zirconium.
 23. The electroplatingsolution of claim 18, wherein the soluble metallic salts includes atleast one refractory metal salt that allows the electrodeposition of arefractory metal.
 24. The electroplating solution of claim 23, whereinthe refractory metal is molybdenum, tungsten, niobium, osmium, hafnium,alloys or combinations thereof.
 25. The electroplating solution of claim18, wherein the soluble metallic salts are a metal alkoxide.
 26. Theelectroplating solution of claim 18, wherein the non-aqueousnon-aromatic organic solvent is a low molecular weight non-aromaticsolvent.
 27. An electroplating system, comprising: a plating chambercontaining an electroplating solution; an entry point to theelectroplating system; and a transporting system to convey a part to beelectroplated from the entry point to the plating chamber, wherein theelectroplating solution includes a non-aqueous non-aromatic organicsolvent and a mixture including soluble metallic salts and organicadditives, the mixture dissolved in the non-aqueous non-aromatic organicsolvent.
 28. The electroplating system of claim 27, wherein the platingchamber includes a single electroplating compartment or a splitelectroplating compartment for an anolyte and a catholyte.
 29. Theelectroplating system of claim 27, wherein the plating chamber includesa split electroplating compartment having two anodes arrangedessentially opposing each other with the catholyte in between, eachanode separated from the catholyte by a membrane.
 30. The electroplatingsystem of claim 27, comprising an external chamber housing molecularsieves and wherein the electroplating solution is continuously agitatedby circulation through the external chamber.
 31. The electroplatingsystem of claim 27, comprising a source of inert gas and an inertatmosphere maintained within at least the plating chamber by gasregulation of the source of inert gas.
 32. The electroplating system ofclaim 31, wherein the inert atmosphere is maintained at a positivepressure.
 33. The electroplating solution of claim 27, wherein thesoluble metallic salts are a metal alkoxide.
 34. The electroplatingsolution of claim 27, wherein the non-aqueous non-aromatic organicsolvent is a low molecular weight non-aromatic solvent.